A metrology system having a specimen stage that can be positioned with high accuracy is useful for numerous measurement tasks. Local measurements can be made with the metrology system in which sensors are fastened to, for example, the specimen stage, in order to position the specimen stage with high accuracy and reproducibility in an optical field to be measured, and to be able to measure the particular optical parameters (for example, intensity or polarization) with positional resolution. If the optical parameter depends on location, a specimen stage that cannot be reproducibly or accurately positioned leads to a measurement error that is obtained as the product of the positioning error multiplied by the gradient of the parameter to be measured.
The metrology system can also be used for length measurement or to measure distances. For example, the object to be measured may contain two distinguishing marks whose separation distance is to be measured. The object can be positioned on the specimen stage, and each of the markings may be positioned at a reference point by using the specimen stage, which may be within the image range of, for example, a microscope. From the photographs of the two marks in combination with the measured positions of the specimen stage, the distance between the marks can be determined as the difference between the two measured positions. It is also possible to move the microscope relative to the object to be measured by means of the specimen stage, or to move both the microscope and the object to be measured. The specimen stage is calibrated if it can be positioned reproducibly but inaccurately.